The present invention relates to a connecting rod with tongue and groove joints between its head and cap.
It is known to join a connecting rod cap to its head via tongue and groove connections in order to prevent joint slippage and screw bending. In a known connecting rod, the tongue and groove joint nearest the shank is a press-fit joint while the other joint is a slip-fit joint. This slip joint does not positively locate the cap with respect to the rod and therefore, shifting or misalignment along the joint split line and cap twisting during bolt tightening can occur. This joint shifting may cause high loading on rod bearings and an out-of-round bearing bore, both of which contribute to increased wear and reduced durability. Similarly, if the cap twists relative to the head during assembly, then clearance between the connecting rod and the crankshaft can be lost with the resulting possibility of engine seizure.